Benzimide-azolon arsonic acids and process for preparing the same



Patented June 19, 1928.

-U NITED STATES PATENT OFFICE.

ALFRED FEHRLE, OF SODENrON-THE-TAUNUS, GERMANY, ASSIGNORS TO I. G. FAR- IBENINDUSTRIEAKTIENGESELLSCHAFT, OF FRANKFORT-ON-THE-MAIN, GERMANY,

A CORPORATION OF GERMANY.

BENZIMIDE-AZOLON ARSONIC ACIDS AND PROCESS FOR PREPARl G No Drawing. Application filed July 19, 1926, Serial No.'1 23,589, and in Germany July 31, 1925.

Our present invention relates'to the prep aration of benz inldeazolonarsomc aclds.

By causing phos ene to act upon orthodiaminobenzene-arsonic acids benzimidea zolonarsonic acids are obtained, thus for instance from 3.4 -diaminobenzenearsonic acid the 3.4 benzimideazolonarsonic acid having the formula:

, 03H: I This acid difi'ers only slightly as to its therapeutic efiicacy from the aromatic arsonic acids hitherto used in medical practice.

sonic acid and 4-amino-3-methylphenylarsonic acid have a lower therapeutic eflicacy than the p-arsanilic acid. Similar experiments were made regarding dyestufi's. Therefore the general conclusion was drawn that the entrance of a methyl group into those compounds impairs their therapeutic action.

But contrary to the experiments above referred to, the acids hereafter described are of ahigher therapeutic efiicacy than the nonsubstituted 3.4-bensimdeazolonarsonic acid.

The following example illustrates our invention, but is not intended to limit it there- O 11, 6 parts by weight of 3-amino-4-methylaminobenzenearsonic acid, obtained by reduction of the corresponding nitroacid (see Bertheim Berichte vol. 44 (1911) 3095 and Bauer Berichte .vol. 48 (1915) page 517) are dissolved in 210 partsby'vollune of a 2 N. solution ofsodium acetate and while stirring phosgene is introduced, whereupon the benz- (4-methyl) -imideazolonarsonic acid 'separates in the form of crystals.

The resulting acid is washed with water and recrystallized froin Water or it is purihydrochloric acid.

In an analogous manner from 3-chloro-4- nitrobenzenearsonic acid or 3-nitro-4-chloro-. benzenearsonlc acid the former prepared by 4 treating 3-chloro-4-nitraniline with arsenic according to Bart) there are produced the corresponding homologous or alkylene substituted benzimideazolonarsonie acids by causing the first mentioned acids to act upon such compounds as ethylamine, propylamine, allylamine, benzylamine and by reducing subsequently the nitro group and treating the reduction product so obtained \with phosgene.

Such homologous or alkylene substituted benzimideazolonarsonic acids are for ininstance:

2*.4 -'benz (4 propyl) imideazolonarsonic acids which is rather diflicultly soluble in water, soluble in methyl alcohol and insoluble in acetone, having its melting point at 280.

3.4-benz- (4-al1yl -imideazolonars0nie acid which is capable 0 being recrystallized from water, insoluble in acetone, soluble in wood alcohol, having its melting point at 280.

3.4-benz- (4-b e n z y, l) -imideazolonarsonic acid which is very diflicultly soluble in water, more readilysoluble in Ynethyl alcohol, 'in-' soluble in acetone, melting point 280 C.

3.4-benz- (3-m e t h yl) -imideazolonarsonic acid which is difiicultly soluble in methyl alcohol, capable of being recrystallized from water, insoluble in acetone. -Melting point 280 C.

, We claim: r

1. "Process for preparing benzimideazolonarsonic acids, which consists in causing phosgene to act upon benzenearsonic acids of the general formula a T-T 0 on As-Ar .wherein Ar stands for aryl and R for methyl-imideazolonarsonic acid, which consnsts in causlng phosgene to' act up n the compound of the formula:

mm 3. As new preducts, the benzimideazolonarsomc acids of the'formul a: 7

R I l v wherein .R stands for alkyl or alkylene and Ar stands for aryl.

' 4. As a new product, "the SA-benZ-QL- methyl)-imideazolqnarsonic acid 'of the formula AsowH In testimony whereof, we afiix our signa- 

